Process for removing phenol from a phenol-containing oil



Dec. 18, 1962 w. HRINGKLEE PROCESS FOR REMOVING PHENOL FROM APHENOL-CONTAINING OIL Filed May 22. 1959 niteol States ltatent QhticeFatenteol Dec. lil, i952 reattori rustico .llnly il, i958 3 Claims (El.Zm-Zd) This invention relates to a continuous process for recoveringphenols from phenol-cntaining liquids. Phenols are recovered on a largescale in low temperature carbonizing installations, coking plants,hydrogenating plants and mineral oil factories by separation fromphenol-containing tars and oils as well as from phenol Waters.

The sodium hydroxide process is generally used for the separation of thephenols from tars and oils. ln this process the phenolic components areextracted with the sodium hydroxide solution. The phenolate liquorobtained is then steam cleaned with water vapor until the dissolvedneutral oils are removed and then treated with CO2 gas. ln this processthe free pbenols are obtained in the form of a crude phenol oil and anaqueous soda solution, the so-called carbonate liquor. The crude phenoloil is processed into the desired phenol products While the carbonateliquor is regenerated by treatment with roasted lime into sodiumhydroxide. The latter is introduced into the process again afterseparation o'r` slaled lime.

This sodium hydroxide process, however, exhibits certain disadvantages.These lie particularly in the laborious regeneration of the carbonateliquor which is quite expensive. Therefore, there has been no dearth ofsuggestions for replacing the sodium hydroxide with more easilyregeneratable salt solutions or with selective solvents.

The Pbenosolvan process has obtained significant acceptance in the artfor recovering phenols from the phenol Water. This process is based onan extraction of the phenolic waters with an ester mixture consistingessentially of butyl acetate. The phenol-containing extract solutionthus obtained is processed by distillation. in this distillation thebutyl acetate is removed and there remains behind a phenol oil whichstill contains several percent of neutral oil that cannot be separatedby distillation. This neutral oil content of the Phenosolvan extractprevents the direct processing to the desired pure phenol products andnecessitates a special oil removal step. This was previously attainedmost safely by redissolving the Phenosolvan extract in sodium hydroxidefollowed by a steam-cleaning step of the phenolate liquor so formed. Toseparate the phenols from this liquor it is then necessary to carbonateit. Carbonate liquor is then collected which is subjected to treatmentwith a caustic in the usual manner for the purpose of regeneration. Theworking steps are therefore approximately the same as in theabove-described sodium hydroxide procedure and, thus, this method of oilremoval also brings with it the same disadvantages.

A signicant advance over the procedures above described was achieved bythe so-called soda-pressure procedure (lit. Bemmann, Chemical Technique,vol. 8, No. l0, pp. 578-579, 1956; Freiberg Research Pamphlets, A 5l,pp. 89-l05, 1956; see also German Patent 1,005,080, Australian atent207,666; Belgian Patent 542,9l9; French lhatent 1,136,187; Polish Patent40,191; Spanish Patent 228,517; South African Patent 3786/55). Thisavoids the disadvantageous procedure of the caustic treatment step. Theprocess is applicable to the separation of the phenols fromphenol-containing oils as Well as for the oil removal of neutraloil-containing crude phenol oils. lt utilizes the fact that an aqueoussoda solution splits into NaQH and CO2 under pressure and increasedtemperatures in a continuous process which operates practically Withoutconsumption of chemioil to be freed ot phenol, or the phenol oil to befreed ot oil, is treated in a column under pressure and at increasedtemperature with an approximately 10% soda solution. Under the operatingconditions, the soda splits in the manner stated and the sodiumhydioxide formed reacts with the phenols to form phenolate liquor.rl`his collects in the bell ot the column where it is heated indirectly.The Water vapor formed in this causes a clean steaming of the phenolateliquor. if, as in the case of the phenol removal from an oil, there is alarge excess of neutral oil present, this process can be supplemented byblowing steam into the sump. The neutral oil vapors and the Water vaporpass over the head of the column together with the carbonio acidproduced in the process and condense in a cooler. The neutral oil andcondensate water are collected and separated in a separatory containerby reducing the pressure. The carbonio acid separated on reducing thepressure is used to carbonate the phenolate liquor Withdrawncontinuously from the bell. rEhe carbonate liquor so formed aftercombination with the condensate Water that has passed over the head isreturned to the process in place of alkali carbonate solution.

The separation of phenols and neutral oils is simplied very much by thisprocedure. lt operates completely continuously and the annoying caustictreatment procedure is eliminated. Also none of the auxiliary substancesneed be supplied from outside the system (CO2 and caustic lime) anymore;only an energy supply in the form of steam is required. instead of sodasolution another suitable alkali carbonate solution can also be used inthe procedure.

1n the operation of such installations experience has shown that in thecase of the phenol removal. from plie ncl-containing oils, it is notalways possible to obtain a sutliciently neutral oil-tree phenolateliquor. Moreover, a large quantity of phenol Water is collecte-d whichis produced through the direct blowing of steam into the columns. On theother hand, it was found that in the oil removal from Phenosolvanextracts by this procedure, considerable quantities of phenols arecontained in the condensate oil.

lt has now been found that these disadvantages may be avoided and thatthe process can be made more economical and effective by the operationot two pressure columns using the technique of the soda pressureprocess, wherein one column is used to separate oil from thephenol-containing oil and wherein the second column is coupled with thefirst column and is used to separate the neutral oils from phenolateliquor produced in the rst column. More particularly, in accordance withthe present invention, it has been found that the disadvantages ot theprior art processes can be avoided and the soda pressure procedure whichis carried out using alkali carbonate solution (preferably sodasolution) under increased pressure and at temperatures above C., can bemade more economical and elective if tvvo pressure columns are employedWorking side by side according to this principle, in one of which thephenol removal from phenol-containing oils is undertaken and in theother the oil removal from neutral oil-containing phenol oil, and it onecouples them to each other in the following manner: the soda solutionneeded in both columns is led in a common cycle and the neutraloil-containing phenol oils collected in the phenol-removing col- 1aCillo.

umn as well as the phenol oil-containing condensate oils collected inthe oil removal column are in each case processed further in the othercolumn.

The procedure according to the invention, therefore,

ermits preparing a phenol-free oil 'from a phenol-containing oil, andfreeing a neutral oil-containing phenol oil of neutral oil, whereby bothstarting products can be processed simultaneously.

It is accordingly an obiect of the present invention to provide animproved process for separating phenol from phenol-containingl oil usingbasically the soda-pressure process but providing an improvement thereinresulting in the avoidance ot the disadvantages inherent in saidsodapressure process, and to increase the effectiveness and improve theeconomy of this process.

@ther and more detailed objects will be from the following descriptio-nand claims.

Referring to the drawings, there is illustrated a schematic system forcarrying out the present invention; columns l and ll are two pressurecolumns which are operated in accordance with the above-describedsoda-pressure procedure.

Column l is operated at a pressure of about l0 atmospheres and at atemperature of about l80 C. rhe phenoi-containing oil such as `a mediumheavy oil having a phenol content of about l5 to 20% is introduced intopressure column l by means of line 2. Sodium carbonate solution isintroduced into column l by line 4. rlhe sodium carbonate solutionintroduced by line fl is obtained from storage tank 6 which stores thecirculating carbonate liquor. ln column l, as a result of the pressureand temperature therein, the aqueous sodium carbonate solutiondissociates in accordance with the following equation:

The sodium hydroxide produced in this reaction reacts with the phenolcontained in the oil to form the sodium phenolate solution. The Volatilematerials such as the phenol-tree oil, carbon dioxide and somephenol-containing water distill from pressure column l and are collectedor recycled. Thus, the phenol-free oil is collected in tank 3 from whichit may be pumped by means of pump l@ to a motor fuel processing plant.Some water containing phenol `which distills from column l is conductedby line l2 to container le where it may be mixed with fresh alkalicarbonate. The CS2 gas is lead by means of line lo to a carbonatingchamber l described in more detail below. Water from the pressure tank lis also introduced into line tl carrying carbonate liquid fromcarbonating container l by means of line 22.

The phenolate liquor produced in pressure tank column l is collected incarbonating chamber lll where it is carbonated by CO2 entering thecarbonating chamber by means of line 16. The purpose of the carbonatingprocedure is to convert the sodium phenolate produced in pressure columnI to free phenol. This reaction is illustrated by the followingequation:

The crude phenol-containing neutral oils are separated from thecarbonate liquor in carbonating chamber l, the crude phenol beingconveyed by means or" line 24 to pressure column II. The carbonateliquor is conducted by line to storage tank o. During its course, thiscarbonate liquor, as described above, is diluted with water enteringline 2d by means ot line 22,

As noted above, the crude phenol-containing neutral oil is introducedinto pressure column ll by means of line 24. Circulating carbonateliquor is tapped from the carbonate circulating storage tank e by meansof line 2% and introduced into pressure column ll. The neutraloil-containing phenol is treated in pressure column ll with the eascirculating liquor under substantially the same conditions as thoseemployed in pressure column l. Here the neutral oils are substantiallydistilled from the crude phenol together with C93 and water. These areseparated, the C02 being returned to a second carbonating chamber 28 andthe water being returned to li e for storage in circulating liquorstorage tan o.

rl`he phenolate prod ct from pressure column ll is carbonated in secondcarbonating chamber 23. The carbonate liquor formed in chamber isconveyed by means of line and line 32 to circulating liquor storage tankn. The phenol containinGf lic, or is conducted from the secondcarbonating chamber to an after carbonating treatment in container T.the phenol oil free of neutral oil is conveyed to stor tank 3d and thenpumped to a furtl1 phenol processi g unit, not shown, by means of pump'lh-e oil condensate leaving second pressure tank ll contains somephenol which is recycled by line 3S to phenol feed line 2 fl/here it isreintroduced into pressure column l.

As described above, the water condensate containing excess phenol whichleaves column and is carried by line l2 is not introduced into thecirculating liquor as such. lt is, however, used to make up fresh sodasolution which is needed to compensate for the small losses incirculating liquor.

The present process is by no means limited to the simultaneousprocessing of the two starting products. The installation described canalso be operated when the supplying of one or other Startins product isoccasionally stopped.

Finally the process can be used only when one of the two products is tobe processed. Then for the purpose of phenol removal from aphenohcontaining oil the latter is freed of phenol in the one of the twopressure columns, the neutral oil-containing phenol oil collected inthis process is freed of oil in the second column operating by the sameprinciple, and the phenol-containing condensate oil separated in thisagain led to the phenol removing column for the separation of thephenols.

lf a neutral oil-containing phenol oil is to be merely freed of neutraloil, then this phenol is freed of oil in one of the two columns, thephenol-containing condensate oil collecting in this process is freed ofphenol in the second column operating by the same principle, and theneutral oil-containing phenol oil separated in this led to the oilremoving column again for the purpose of separating the neutral oils.

In these cases, the second column in each case, which serves either forthe oil removal of the phenol oil produced in the phenol removal fromthe oil, or else for the phenol removal from the condensate oilcollected in the oil removal from the phenol, is dimensioned correspondingly smaller.

Columns l and il can be operated over a Wide range of conditions. Thus,the temperature in each column can be maintained in the range ot 169 C.to 226 C. The pressure can also be varied considerably in the columns.By way of illustration, they can range trom 6 to 24 atmospheres otpressure.

Similarly the rate of feeding the crude phenol containing liquid to thesystem varies. ln general, the crude phenol containing liquids are fedat a rate of about 200 to 400 liters per hour.

present process is applicable to the processing of a wide variety ofphenol containing liquids, particularly oils. Among the products thatmay be treated may be mentioricd:

ln the phenol separation column, for instance, carbolic oil, mediumheavy oil from hydrogenation plants, light oil from lignite coking.

ln the oil separation column 5, for instance, crude phenols containingneutral oils, l3 ienosolvan extracts.

The tollov examples Lare further illustrative of the present invention.It is to be understood, however, that the invention is not limitedthereto.

Example 1 Two pressure columns used in the conventional pressuresodaprocess for recovering phenol from phenol containing oils were run at asump temperature of 180 C. and a pressure of atmospheres. One of the twopressure columns (the phenol separating column I) was fed hourly 300liters of medium heavy oil containing 18.6% phenol and obtained from alignite hydrogenation process, and 400 liters of a 10% soda solutionobtained from the cyclic liquor storage container which collects liquorfrom both columns. into the other column (the oil separating column Il)was fed hourly 400 liters of crude phenol oil containing 2.2% neutraloil and 1600 liters of the 10% soda solution circulating liquid. In bothcolumns the pressure soda process proceeds. The phenols are separated asphenolate liquor and the steam resulting from the heating of the liquidinjected into the columns draws the non-phenolic portion of the startingproduct overhead. From phenol separating column I, 280 liters per hourof rie-phenolated medium heavy oil are obtained which still contain aresidual phenol content of 1.7% consisting of cresols and Xylylols. Thisis converted into a motor fuel by a subsequent hydrogenation treatment.The phenolate liquor resulting from the phenol separating step iscarbonated with the aid of the carbonic acid which is vented from columnI. The phenol oil obtained in this manner contains 2.9% neutral oil.

Because of its high neutral oil content, this product is unsuitable forworking up to a phenol product. For this reason, the crude phenol oil issubjected to a continuous de-oiling step in column II.

A practically neutral oil-free phenolate liquor is drawn ott fromdeoiling column Il. This is carbonated with the help of the carbonioacid which is vented from this column and then subjected to an aftercarbonation treatment. There results a neutral oil-free phenol oil whichcan be directly worked up to a product of standard purity. The oilcondensate, which is obtained from the head of the column in quantitiesof l./h. and contains 45% of phenolic constituents, is recycled to theoil which is being continuously introduced into dephenolating column I.

The Water of condensation obtained from the head or" each column (column1 180 l./h., column II-200 l./ h.) is separated from the oil condensateand is continuously added to the concentrated soda solution (carbonateliquor) which is separated from the carbonated or after carbonatedphenolate liquor. The soda solution recovered reaches the commoncirculating liquor storage container from where it is introduced intothe columns anew.

lf the steam clarification step in column I is to be supplemented by thedirect introduction of steam, which at most will be in quantities of20-30 kg./1., the dilution of the circulating liquor will be compensatedfor by conduct ing a corresponding quantity of water of condensation toa separate container where it is used to prepare fresh soda solution.

Following the same procedure outlined above, any of the crudephenol-containing liquids mentioned above may be treated.

While the invention has been described with particular reference tospecific embodiments, it is to be understood that it is not limitedthereto, but is to be construed broadly and restricted solely by thescope of the appended claims.

What is claimed is:

l. A process for removing phenol from an oil containing the same and ofremoving oil from phenol containing the same which comprisesestablishing a rst and second pressure zone and an alkali carbonateliquor storage zone, maintaining said rst and second pressure Zones atelevated pressures from 6-24 atmospheres and at temperatures above fromi-220 C., introducing said oil which contains some phenol into saidiirst pressure Zone, conveying alkali carbonate solution from saidstorage Zone into said irst pressure zone whereby a reaction is causedto take place in said zone forming a rst phenolate liquor while oil freefrom phenol, H2O and CO2 are distilled off, carbonating said rstphenolate liquor, whereby a iirst carbonate liquor layer and a rstphenol liquor layer containing some neutral oils are formed, separatingsaid two layers, conveying said rst phenol liquor with the neutral oiltherein to said second pressure zone, conveying said rst carbonateliquor layer to said storage zone, conveying alkali carbonate solutionfrom said storage zone to said second pressure zone, wherein itencounters and reacts with said first phenol liquor layer containingneutral oil, whereby a second phenolate liquor is formed and neutraloils, CO2 and H2O are distilled from said second pressure zone, and arereturned to said iirst pressure Zone, carbonating said second phenolateliquor, whereby a second phenol liquor-containing layer and a secondcarbonate liquor layer are formed, separating said layers and conveyingsaid second carbonate liquor layer to said storage zone. f

2. A process according to claim 1 wherein CO2 distilling from said lirstand second pressure zones is used respectively to carbonate said rst andsecond phenolate liquor.

3. A process according to claim 1, wherein condensed water obtained fromdistillation in said first pressure zone is employed to make up freshalkali carbonate liquor for use in the circulating liquor system.

References Cited in the iile of this patent UNITED STATES PATENTS1,944,681 Cooper Ian. 23, 1934 2,203,217 Hund et al .Tune 4, 19402,246,376 Lynch June 17, 1941

1. A PROCESS FOR REMOVING PHENOL FROM AN OIL CONTAINING THE SAME AND OFREMOVING OIL FROM PHENOL CONTAINING THE SAME WHICH COMPRISESESTABLISHING A FIRST AND A SECOND PRESSURE ZONE AND AN ALKALI CARBONATELIQUOR STORAGE ZONE, MAINTAINING SAID FIRST AND SECOND PRESSURE ZONES ATELEVATED PRESSURES FROM 6-24 ATMOSPHERES AND AT TEMPERATURES ABOVE FROM160-220*C., INTRODUCING SAID OIL WHICH CONTAINS SOME PHENOL INTO SAIDFIRST PRESSURE ZONE, CONVEYING ALKALI CARBONATE SOLUTION FROM SAIDSTORAGE ZONE INTO SAID FIRST PRESSURE ZONE WHEREBY A REACTION IS CAUSEDTO TAKE PLACE IN SAID ZONE FORMING A FIRST PHENOLATE LIQUOR WHILE OILFREE FROM PHENOL, H2O AND CO2 ARE DISTILLED OFF, CARBONATING SAID FIRSTPHENOLATE LIQUOR, WHEREBY A FIRST CARBONATE LIQUOR LAYER AND A FIRSTPHENOL LIQUOR LAYER CONTAINING SOME NEUTRAL OILS ARE FORMED, SEPARATINGSAID TWO LAYERS, CONVEYING SAID FIRST PHENOL LIQUOR WITH THE NEUTRAL OILTHEREIN TO SAID SECOND PRESURE ZONE, CONVEYING SAID FIRST CARBONATELIQUOR LAYER TO SAID STORAGE ZONE, CONVEYING ALKALI CARBONATE SOLUTIONFROM SAID STORAGE ZONE TO SAID SECOND PRESSURE ZONE, WHEREIN ITENCOUNTERS AND REACTS